JP2007256798A - Optical module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture an optical module without being restricted in strength and accuracy, and to enable its PC contact part to have sufficient durability, in an optical module for coupling an optical device with an optical connector. <P>SOLUTION: The sleeve 1 of the optical module is composed of: a ferrule receiving part 11 for receiving a ferrule accompanying to an optical connector; a device package receiving part 13 for receiving the package of the optical device from the opposite side in the direction inserting the ferrule in the ferrule receiving part 11; a through hole which is situated between the ferrule receiving part 11 and the optical device package receiving part 13 and which secures an optical path between the optical connector and the optical device; and a window part 14 which blocks the through hole and which, when the ferrule is inserted, comes in contact with the end face of the optical fiber with the surrounding covered by the ferrule, wherein the material of the window part 14 is made of a resin. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical module for optical communication that receives an optical connector.

  In an optical module used for optical communication using an optical fiber, an optical signal emitted from the optical device is transmitted to the optical fiber, or an optical signal transmitted through the optical fiber is condensed on the optical device. An optical signal from an optical device (mainly LD: Laser Diode) that is a light emitting element needs to be collected on a core that is a waveguide of an optical fiber. Further, in an optical device (mainly PD: Photo Diode) that is a light receiving element, an optical signal transmitted through the core of the optical fiber is collected by a lens or the like, received by the optical device, and converted into an electrical signal.

  As such an optical module, Patent Document 1 discloses an optical coupling component that connects an optical fiber and an optical device used in TOSA (Transmitter Optical Sub-Assembly) and ROSA (Receiver Optical Sub-Assembly). .

  As shown in FIG. 7, the optical coupling component 70 includes a sleeve 71 that receives an optical ferrule 73 that includes an optical fiber 74, and an optical device receiving portion that receives an optical device 76 from the opposite side of the sleeve 71. 75, and a fiber contact portion 77 formed between the sleeve 71 and the optical device receiving portion 75 and having a convex shape on the sleeve 71 side and an inclined side on the optical device receiving portion 75 side.

Here, the sleeve 71, the optical device receiving portion 75, and the fiber contact portion 77 are integrally formed. Since the fiber contact portion 77 is formed in a convex shape, when the ferrule 73 is inserted into the space 72 formed by the sleeve 71, the convex surface can be physically contacted with the optical fiber 74 (PC contact). . In addition, when the light emitted from the LD is collected by the optical lens and coupled to the optical fiber 74 by the inclined surface 78 of the fiber contact portion 77, the reflected return light generated at the end face of the optical fiber 74 is retransmitted to the optical device. It is possible to prevent the operation of the optical device from becoming unstable.
US Pat. No. 6,536,959

  However, in the above-described optical coupling component 70, the sleeve 71, the optical device receiving portion 75, and the fiber contact portion 77 are formed by integral molding, and in Patent Document 1, the material of the fiber contact portion 77 for PC contact is specified. It is not done and feasibility is low.

  For example, when this integrally molded product is molded from glass, it is subject to restrictions on the accuracy of glass molding and strength restrictions caused by the fact that glass is a brittle material. Therefore, the optical module described in Patent Document 1 is very likely to be extremely expensive and low in reliability. Furthermore, molding the sleeve 71 with glass itself is very brittle and cannot mechanically withstand insertion and extraction with a ferrule.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to manufacture an optical module that couples an optical device and an optical connector without being restricted in terms of strength and accuracy, and a PC. It is possible to give the contact part sufficient durability.

  An optical module according to the present invention is an optical module for optical communication that includes a sleeve part and an optical device and receives an optical connector, and the sleeve part receives a ferrule that receives a ferrule attached to the optical connector. An optical device receiving unit for receiving the optical device, a through hole between the ferrule receiving unit and the optical device receiving unit for securing an optical path between the optical connector and the optical device, and the through hole And a window part that contacts the ferrule end face when the ferrule is inserted, and the material of the window part is made of resin.

  According to the present invention, an optical module that couples an optical device and an optical connector can be manufactured without being restricted in strength or accuracy, and sufficient durability can be imparted to a PC contact portion.

  An optical module according to the present invention is an optical module for optical communication that includes a sleeve and an optical device and receives an optical connector, and is used for an optical transceiver, for example. Here, it is assumed that the optical device has a package (CAN package) in which a semiconductor optical element is mounted. First, a sleeve component having a sleeve used in the optical module according to the present invention will be described.

  FIG. 1 is a perspective view showing a configuration example of a sleeve part in an optical module according to the present invention, and FIG. 2 is a perspective sectional view of the sleeve part of FIG.

  A sleeve part 1 shown in FIG. 1 includes a ferrule receiving unit 11 that receives a ferrule attached to an optical connector, and an optical device receiving unit that receives a CAN package from the opposite side of the ferrule receiving unit 11 in the direction in which the ferrule is inserted. The receiving part 13 and the through-hole for ensuring an optical path in the insertion back side (bottom part) are provided. The ferrule receiving unit 11 and the optical device receiving unit 13 are connected by this through hole (also referred to as a coupling hole or a sleeve hole).

  The ferrule receiving portion 11 indicates a hollow cylindrical portion that receives the ferrule of the optical connector, and the cross section of the cylinder is like a cross section 15. That is, by this hollow cylindrical portion, the ferrule receiving unit 11 forms a sleeve that holds the ferrule of the optical connector and determines its position. Further, a flange 12 is formed on the outer surface of the ferrule receiving part 11, and this flange 12 serves as an engaging part with a transceiver housing or the like. By providing a structure in which the flange 12 is sandwiched from the front and the rear on the optical transceiver side on which the sleeve part 1 is mounted, the position of the sleeve part 1 within the transceiver is uniquely determined. Since the optical device 13 accommodates and couples the optical device, it is also referred to as an optical subassembly receiving portion or a coupling portion.

  In addition, as shown in FIG. 2, the sleeve part 1 is a light that covers a through-hole between the ferrule receiving part 11 and the package receiving part 13 and whose periphery is covered with the ferrule when the ferrule is inserted. It has a window part 14 that contacts the end face of the fiber. The window part 14 is a part that is fitted into and engaged with a through-hole opened at the bottom of the ferrule receiving part 11 and transmits light and also plays a role of an anti-reflective part (anti-reflector) as described later. . Therefore, it can be said that the sleeve part 1 is a sleeve part with an anti-reflector.

  In this example, the material of the ferrule receiving unit 11 and the optical device receiving unit 13 (hereinafter referred to as a first material) is different from the material of the window part 14 (hereinafter referred to as a second material). The second material is a resin capable of maintaining the shape for maintaining the optical fiber and the PC contact in the ferrule with a necessary and sufficient durability, such as a silicone resin.

  On the other hand, the first material (sleeve material) can be formed of either resin or metal, and as the former example, it is appropriate to use liquid crystal polymer, polyetherimide, or the like. In the case of metal, it is preferable to use ferritic stainless steel. The ferrule receiving unit 11 and the optical device receiving unit 13 are preferably formed of the same material, but may be formed of different materials (of course, different from the second material) and combined.

  3 is a vertical cross-sectional view of the sleeve component of FIG. 1, and FIG. 4 is an enlarged view of a main part of FIG. FIG. 5 is a view showing a state when the optical connector is connected to the sleeve part of FIG. 4, and shows a state where the window part 14 and the ferrule 40 are in PC contact.

  As shown in FIG. 3, the position of the window component 14 is the position of the through hole 32, and the shape of the window component 14 has an arc portion 21 on the ferrule receiving portion 11 side, and the facing side thereof is perpendicular to the optical axis. It has an inclined surface 20 that is not. The arc portion 21 protrudes from the ferrule abutting surface that is the bottom of the ferrule receiving portion 11, and forms a protrusion 22. Further, the through hole 32 is formed with a step portion 33 along the optical axis, thereby playing a role of preventing the window part 14 from coming off against the ferrule pressing.

  Thus, it is preferable that the end surface on the ferrule receiving portion 11 side of the window component 14 is formed in a convex shape, and the end surface on the package receiving portion 13 side of the window component 14 is the center of the ferrule and the semiconductor optical element. It is preferable that it is the inclined surface 20 with respect to the axis | shaft which connects.

  The window part 14 is preferably made of a resin material such as silicone resin, which is translucent, has a Young's modulus (elastic modulus) of 100 MPa or less, and has a refractive index of 1.4 to 1.5. Cost reduction can be achieved by insert molding in the set state. Further, by using a rubber material having an extremely low Young's modulus, it is possible to solve problems such as excessive compressive stress due to ferrule pressing, permanent deformation caused by the ferrule pressing, and easy damage. . In addition, as a physical property value of a typical silicone resin, a transmittance of 92%, a refractive index of 1.4, and an elastic modulus of 80 MPa at a wavelength of 1.3 μm to 1.5 μm are known. It is relatively easy to change these physical property values depending on the material. Further, as a specific method of insert molding, a method of injecting resin from the cylindrical side surface 23 on the inclined surface side can be considered.

  Further, as described as the protrusion 22, the apex of the arc portion 21 protrudes, for example, by about 0.1 mm from the end surface 31 against which the ferrule 40 abuts, but this is a dimension in consideration of the molding accuracy of the silicone resin.

  Usually, the pressing force from the ferrule 40 is about 4N to 10N. As shown in FIG. 5, the contact interface 42 is flatly deformed into a circular shape, and stress is generated on the surface thereof. In the case where a material having a high Young's modulus such as ceramic or glass is used for the window part 14, the physical contact interface 42 is crushed by this pressing force into a circular shape having a diameter of about 0.1 mm. In this case, even if the load is 4N, the stress value is as high as 500 MPa.

  Therefore, for example, when a conventional glass antireflection component called a vendor is applied, the compression resistance of the molding glass is 200 to 300 MPa, so that permanent deformation occurs beyond the yield limit of the material. On the other hand, when plastic, which is a material used in conventional resin sleeves such as polyetherimide, is applied, the Young's modulus is low, so the contact area increases, and as a result, the stress value generated on the contact surface also decreases. To do. On the other hand, the material hardness of glass is about Vickers hardness of about 500, whereas that of plastic is about 20 at most, which makes it extremely sensitive to scratches caused by fine dust.

  However, the permeable rubber such as silicone resin applied in this example is extremely low at 0.1 GPa or less with respect to Young's modulus of 3.5 GPa of polyetherimide used for the resin sleeve, and it can be said that almost no stress is generated upon deformation. Therefore, it is possible to achieve both stress relaxation and improvement in adhesion of the physical contact surface, and further improvement in resistance to scratches.

  FIG. 6 is a cross-sectional view showing a configuration example of the optical module according to the present invention, and is a diagram showing a state when an optical device is connected to the sleeve component shown in FIGS.

  The sleeve part 1 having the window part 14 described above is assembled with the optical device 2. The optical device 2 is an optical component having an outer shape of a package (also referred to as a CAN package or a TO-package) in which semiconductor optical elements such as LD and / or PD are mounted.

  In the case of the light receiving device, the PD is directly mounted on the metal stem 54, and in the case of the light emitting device, a block is formed on the stem 54 and the LD is mounted on the side surface of the block. An optical element 56 such as a PD or LD is wire-bonded to lead pins 40a to 40e attached to the stem 54, and receives an electrical signal (operation signal, power supply) from the outside or transmits a signal to the outside. In this example, the preamplifier 57 and the capacitor 55 are directly mounted (fixed) on the component mounting surface of the stem 54, and the electronic circuit (the optical element 56, the preamplifier) is considered in consideration of noise resistance characteristics with respect to the signal of the optical element 56. 57, the entire capacitor 55) is accommodated in the package 50.

  A cap 51 is further mounted on the stem 54, and devices such as PD and LD inside are thermally insulated and sealed by the cap 51. The connection between the cap 51 and the stem 54 is generally resistance welding, that is, the stem 54 and the cap 51 are generally made of metal. To condense the light emitted from the LD onto the fiber end (in the case of a transmission module) or condense the light emitted from the fiber end onto the light receiving surface of the PD (in the case of a reception module). The lens 53 is mounted. An adhesive is used to connect the lens 53 and the cap 51 to the ceiling. The lens 53 may be a spherical lens or an aspherical lens as shown in the figure, or may be a non-target lens having different focal lengths on the device side and the fiber side.

  The connection between the optical device (CAN package) 2 and the sleeve component 1 may be performed using an adhesive at a contact portion or a small diameter portion of the cap 51. The sleeve part 1 has a so-called ferrule receiving part 11 for receiving a ferrule as described above and an optical device receiving part 13 for receiving a CAN package, and a window part 14 is formed between the two parts. ing. By making the inner shape of the inner wall 30 of the ferrule receiving part 11 slightly larger than the outer diameter of the inserted ferrule, the ferrule can be smoothly inserted into the ferrule receiving part 11.

  Further, the inner diameter of the optical device receiving portion 13 is larger than the outer diameter of the fitting portion of the CAN package, and the clearance is larger than the relationship between the sleeve inner diameter and the ferrule outer diameter on one side of about 0.1 mm. With the likelihood of this diameter, alignment in a plane perpendicular to the optical axis is performed between the sleeve and the CAN package. The alignment in the direction parallel to the optical axis is adjusted by the amount of the overlapping portion of the optical device receiving unit 13 and the CAN package. It is preferable to apply an ultraviolet curable resin to the inner surface (or outer surface of the CAN package) of the optical device receiving unit 13, align the two in that state, and cure the ultraviolet rays after alignment to fix both. In addition, since the strength may be insufficient only by fixing with an ultraviolet curable resin, in that case, after fixing with an ultraviolet curable resin, a black resin (epoxy resin) is applied to the outer surface of the fixed portion and thermally cured. It is better to secure the strength and secure it. That is, it is good to fix with 2 types of resin, an ultraviolet curable resin and a thermosetting resin.

  In FIG. 6, the shape of the outer periphery of the CAN package has a step at an intermediate portion (contact portion 52 portion). This is to secure the area of the CAN package base, and about 5 mm is necessary. In fact, since the sleeve diameter is generally 1.25 mm, it is sufficient that a diameter of 2 to 3 mm is secured for joining to the sleeve, whereas the device at the base of the package (optical device, electronic device, In addition, since it is necessary to secure a mounting area for electronic components such as capacitance), about 5 mm is required. Moreover, since the diameter of the commercially available TO-package is about 5 mm, it is possible to use a general stem for a CAN package.

  Thus, in this example, the gap of the diameter of both (the connection part of the package root part and the sleeve) is absorbed by providing a step on the outer peripheral surface of the CAN package. This step is eliminated when a general CAN package and a cap associated therewith are used. For the purpose of reducing the size of the entire optical module and reducing the component cost of the optical module, a general (commercially available) CAN package component may be adopted.

It is a perspective view which shows one structural example of the sleeve components in the optical module which concerns on this invention. It is a perspective sectional view of the sleeve component of FIG. FIG. 2 is a vertical sectional view of the sleeve component of FIG. 1. It is a principal part enlarged view of FIG. It is a figure which shows a state when an optical connector is connected to the sleeve component of FIG. It is sectional drawing which shows one structural example of the optical module which concerns on this invention. It is sectional drawing which shows the structure of the optical module by a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Sleeve part, 11 ... Ferrule receiving part, 12 ... Flange, 13 ... Optical device receiving part, 14 ... Window part, 15 ... Cross section of sleeve, 20 ... Inclined surface.

Claims (4)

An optical module for optical communication comprising a sleeve part and an optical device and receiving an optical connector,
The sleeve component includes a ferrule receiving unit that receives a ferrule attached to the optical connector, an optical device receiving unit that receives the optical device, the ferrule receiving unit, and the optical device receiving unit. A through hole to be connected, and a window part that closes the through hole and contacts the ferrule,
An optical module, wherein the window part is made of resin.   The optical module according to claim 1, wherein an end surface of the window part on the ferrule receiving part side is formed in a convex shape.   The optical module according to claim 1, wherein an end surface of the window part on the optical device receiving unit side is inclined with respect to an optical axis of the ferrule receiving unit.   4. The optical module according to claim 1, wherein the window part is made of a silicone resin and has a Young's modulus of 100 MPa or less. 5.

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